Solar Filter Calculator
Size a solar filter for safe sun observation and estimate solar image size and cost by filter type.
Inputs
Results
Filter Diameter
215 mm
≈ 3 credit cards
Est. Cost
$508.00
≈ 9 tanks of gas
Solar Image Size11.2 mm
Safety (1-3)3
How to Use This Calculator
- Enter Telescope Aperture (in), Focal Length (mm), and Filter Type.
- Review Filter Diameter (mm) and Est. Cost ($).
- Use Solar Image Size (mm) and Safety (1-3) to inform your decision.
- Use the chart to visualize the results and explore different scenarios by adjusting inputs.
How the result changes with Telescope Aperture (in)
| Telescope Aperture (in) | Filter Diameter | Est. Cost |
|---|---|---|
| 3.8 | 109 mm | $241.00 |
| 8.3 | 223 mm | $527.00 |
| 14 | 368 mm | $889.00 |
| 18 | 469 mm | $1,143.00 |
What each input means
- Telescope Aperture (in)
- Diameter of your telescope's primary mirror or lens in inches
- Focal Length (mm)
- Focal length of your telescope in millimeters
- Filter Type
- 1 = Glass (ND5 white light), 2 = Film (Baader Astrosolar), 3 = H-alpha (prominences/chromosphere)
How this is calculated
Worked example, using the default values
- Identify Input ParametersTelescope Aperture (in) = 8, Focal Length (mm) = 1200, Filter Type = 1 = 3 input(s) provided
- Calculate Filter DiameterFilter Diameter215 = 215
- Calculate Solar Image SizeSolar Image Size11.2 = 11.2
- Calculate SafetySafety3 = 3
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